I. Field of the Invention
This invention pertains to welts for shoes and more particularly to welts for shoes having soles made from urethane foam.
II. Description of the Prior Art
In the prior art, welts have been extensively used in shoe manufacture to cover a seam formed between a shoe outer sole and a shoe upper. Such welts are provided with upstanding beads at their inner end which are deformed by the shoe upper such that the shoe upper and beads are close fitting thereby covering the seam and also providing an obstacle against water attempting to migrate to the stitching of the shoe. The welt is bonded to the shoe sole and to the upper of the shoe to strengthen the joint.
Prior art shoe welts are shown in the following U.S. Pat. Nos.: 2,438,095; 2,753,636; 3,113,388; 2,563,638; and 2,448,165. Such prior art shoe welts have several features in common. First, the welts have a horizontal body portion to be bonded to an upper surface of a shoe outer sole along the shoe upper. Commonly, such welts are provided with upstanding beads along an inner edge of the body portion with the bead abutting the surface of the shoe upper. Such prior art welts further include stitch receiving grooves along the bottom of the body portion near the inner edge. The stitch receiving grooves accommodate stitching which secures the welt to the shoe upper and to the shoe insole.
While some of the aforementioned patents show shoe welts having portions extending vertically downwardly from the inner end of the body portion, these portions are typically trimmed before the shoe welt is secured to the shoe outer sole. Typically, the shoe welt is secured to the outer sole by stitching.
The aforementioned U.S. patents are applicable to shoes having leather outsoles where the shoe welt may be readily stitched to the outsole. Today, the shoe manufacturing art includes not only leather shoe soles but also shoe soles which are formed from hardened urethane foam. In such shoes, the shoe welt is not stitched to the shoe sole but is attached to the urethane foam by adhesion as the foam hardens. However, a good bond between the sole and the welt is not always achieved. A possible explanation for the lack of a good bond may be the presence of air bubbles between the foam and the welt. In such cases, the welt may break away from the urethane sole after a period of use.